The effect of the moisture content of a local heat source on the blood flow response of the skin

Abstract

Numerous studies have examined the effect of local and global heating of the body on skin blood flow. However, the effect of the moisture content of the heat source on the skin blood flow response has not been examined. Thirty-three subjects, without diabetes or cardiovascular disease, between the ages of 22 and 32 were examined to determine the relationship between the effects of dry vs. moist heat applied for the same length of time and with the skin clamped at the same skin temperature on the blood flow response of the skin. The skin, heated with an infrared heat lamp (skin temperature monitored with a thermocouple) to 40 degrees C for 15 min, was either kept moist with wet towels or, in a separate experiment, kept dry with Drierite (a desiccant) between the towels to remove any moisture. Before and after heat exposure of the forearm, blood pressure, heart rate, skin moisture content, skin temperature, and skin blood flow were recorded. The results of the experiment showed that there was no change in skin moisture after 15 min exposure to dry heat at 40 degrees C. However, with moist heat, skin moisture increased by 43.7%, a significant increase (P < 0.05). With dry heat, blood flow increased from the resting value by 282.3% whereas with moist heat, blood flow increased by 386% over rest, a significant increase over dry heat (P < 0.05). Thus, with a set increase in skin temperature, moist heat was a better heating modality than dry heat. The reason may be linked to moisture sensitivity in calcium channels in the vascular endothelial cell.

Comparison of Different Heat Modalities for Treating Delayed-Onset Muscle Soreness in People with Diabetes

“…[36][37][38] Unlike hydrocollator heat wraps, these chemical heat wraps apply moist heat directly to the skin where latent and conductive heat provides rapid heat transfer deep into tissue. 37,38 Hydrocollator heat packs (Chattanooga E1, Chattanooga, TN) produce moisture, but much of the moisture is buffered by the six to eight layers of towels under the wraps. This mixes moist heat with conductive heat such that pure moist heat on the skin is not present.…”

Skin Moisture and Heat Transfer

“…Older people have thinner dermal layers than that found in younger people [ 69,95,106 ] . This Each fi gure shows the skin and muscle temperature.…”

“…This receptor has multiple binding sites and senses such factors as temperature, pressure, and osmolarity [ 83,95 ] . TRPV channels are expressed in smooth muscle cells, endothelial cells, as well as in perivascular nerves [ 5 ] .…”

“…To date, six phosphorylation sites on ENOS have been identifi ed, including serine 1,177, threonine 495, protein kinase b (pkb-akt) 939, adenosine monophosphate-activated kinase, protein kinase A, and protein kinase G [ 70,107 ] . For example, the ENOS cascade can be activated by receptors for estrogen and glucocorticoids [ 95 ] , insulin and vascular endothelial growth factor (VEGF) [ 4 ] , and blood fl ow and laminar shear stress [ 3,24 ] .…”

The Effect of Type-2-Diabetes-Related Vascular Endothelial Dysfunction on Skin Physiology and Activities of Daily Living

“…[74][75][76] These neuropeptides are released when TRPV-1 voltage-gated calcium channels in skin tactile sensory receptors become active. 77,78 The release of neuropeptides then causes relaxation of vascular smooth muscle. The sustained skin vasodilation that occurs after the first few minutes of heat exposure is mediated by nitric oxide Figure 3.…”